Abstract
A simple colorimetric sensor array based on red-emitting CdTe QDs and green-colored fluorescein that exhibited RGB-type color change was proposed for visual detection of trace formaldehyde. In the presence of formaldehyde, the red fluorescence from CdTe QDs was quenched while the green fluorescein was inert thus as a reference. Through harvesting the varied quenching efficiency of different ligand-capped CdTe QDs by formaldehyde, a simple sensor array can be constructed for both selective detection of formaldehyde with high sensitivity (LOD of 0.08 ppm) and identification of the existence of potential interference from acetaldehyde. The quenching mechanisms of formaldehyde toward different ligand capped CdTe QDs were studied with fluorescence lifetime, zeta potential, and also theoretical calculations. The results from theoretical calculations were in good agreement with the experimental results. The proposed sensor array was successfully explored for visual analysis of formaldehyde in indoor air samples.
Highlights
Quantum dots (QDs) have received great attention in sensor applications, luminescent biolabels, and bioimaging probes[1,2,3,4]
Traditional techniques used for formaldehyde detection are based on gas chromatograph, mass spectroscopy, fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectrometry (UV/Vis) and fluorimetry[28,29], which are inconvenient for on-site direct visual readout
CdTe QDs were selected since they can be facilely synthesized via aqueous synthetic routes with high fluorescent yield[30]
Summary
Quantum dots (QDs) have received great attention in sensor applications, luminescent biolabels, and bioimaging probes[1,2,3,4]. RGB (red, green and blue)-based color change has been extensively explored in sensor development since the analyte response can be directly and sensitively read out with naked eye[17,18,19]. Ratiometric sensing with “traffic light”-type response, i.e., encoding the signal with one color as the signal code and another as the reference, is a typical application of RGB for visual analysis[22,23]. We proposed a simple RGB-type sensor array based on color modulation of different ligands-capped CdTe QDs. Formaldehyde was selected as a model analyte, which has been discussed as a typical indoor pollutant for decades[28,29]. Reading out of formaldehyde can be achieved via color change of the sensor array
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